This invention relates generally to electromagnetic fuel injectors. More specifically it relates to a new and unique flat seat and needle fuel seal in an electromagnetic fuel injector.
The fuel injector that is illustrated in U.S. Pat. No. 4,610,080, commonly assigned, is representative of one known type of fuel injector. The needle has a rounded tip that seats in a frusto-conically shaped hole that is centrally located in a seat member that disposed at the tip end of the injector. A guide member is affixed to the interior face of the seat member and comprises a hole that is accurately aligned to the frusto-conical hole in the seat member. As the needle is displaced by operation of the injector's electromagnetic solenoid, the hole in the guide member guides the needle axially into and out of seating engagement with the frusto-conical hole in the seat member. The guide member has several holes that are located radially outwardly of its central guide hole, and these several holes serve to convey fuel past the guide member and toward the seat member.
The present invention relates to a new construction for the seat member and the needle wherein the two are constructed to have what are essentially flat parallel mating surfaces that provide a good initial seal when the injector closes and whose interface plastically conforms during continued operation of the injector to produce an even better seal. The invention provides improved sealing over the life of the injector, de-sensitizes the fuel flow vs. stroke characteristic of the injector, and reduces the alignment sensitivity resulting in reduced dependency on precision manufacturing operations. The invention also provides a particle trap that can reduce the chances of a foreign particle falling between the needle and seat.
The foregoing features, advantages, and benefits of the invention will be seen in the ensuing description and claims which should be considered in conjunction with the accompanying drawings. The drawings disclose a preferred embodiment of the invention in accordance with the best mode contemplated at the present time in carrying out the invention.